Custom domain doesn't work

I built a website, and bought a domain from
I have deployed the website to netlify, and add the custom domain, so it worked well, but it suddenly stopped working 5 days ago. I tried to fix it, but I couldn’t find out what the problem.
So I redeployed the website to Netlify, and added custom domain, update the domain name servers on 2 days ago. However, it has been 24 hours, but the site has not yet lived.
I need your help.

My custom domain:

@Brian Welcome to the Netlify community.

Your DNS is delegated to Cloudflare, and Cloudflare is not pointing (or not pointing correctly) at your Netlify site.

If you decide to keep Cloudflare for whatever reason, you must turn OFF protection (gray cloud instead of orange cloud).

I have a question.
Should I setup DNS on cloudflare for all Nelify deployed website?

@Brian No, not unless you have a use-case in which that would be the best approach.

What should I enter to the name servers field of bought my custom domain here) when I configure external DNS for a custom domain?